"What lies beneath the mask" is a special research quest in the game Pokémon Go, which is themed around the ghost-type Pokémon Yamask. The quest is part of the Halloween 2021 event and is not time-limited, meaning that players can complete it at any time. The quest consists of four stages, each with three individual challenges. The tasks and rewards for each stage are as follows:

Stage 1

• Catch 40 Ghost-type Pokémon (400 Stardust)
• Transfer 9 Pokémon (Duskull Encounter)
• Make 49 Nice Throws (9 Ultra Balls)
• Rewards: Yamask Encounter, 4,000 XP, 9 Nanab Berries

Stage 2

• Catch 40 Ghost-type Pokémon (Pikachu Encounter)
• Make 9 Curveball Throws (490 Stardust)
• Use 49 Berries to help catch Pokémon (Banette Encounter)
• Rewards: 13 Yamask Candy, 4,900 Stardust

Stage 3

• Catch 40 Ghost-type Pokémon (Gastly Encounter)
• Make 9 Great Throws (490 Stardust)
• Use 49 Berries to help catch Pokémon (Misdreavus Encounter)
• Rewards: 13 Yamask Candy, 4,900 Stardust

Stage 4

• Claim reward (49 XP)
• Claim reward (49 XP)
• Claim reward (49 XP)
• Rewards: Galarian Yamask Encounter, 4,000 XP, 9 Pinap Berries

Players are advised to complete the quest during the Halloween event, as ghost-type Pokémon will be appearing more frequently, making it easier to complete the ghost-type related tasks. It is also recommended to stockpile berries before completing the second stage of the quest, as a significant number of berries are required to complete it.